The present invention relates generally to interconnect adapters and more specifically to a BMA interconnect adapter using a bulkhead mountable BMA connector.
Electronic measurement equipment, such as oscilloscopes, spectrum analyzers, network analyzers and the like, and signal sources, such as arbitrary waveform generators, microwave generators and the like, use a variety of signal connectors for coupling signals into and out of the measurement equipment and signal sources. BNC connectors have a bayonet type connecting mechanism for securing the male side of the BNC connector to the female side of the connector. SMA, APC-7 and N-type connectors have threaded connecting mechanisms for securing the male side of the connectors to the female side. The female sides of the connectors have a threaded outer surfaces for receiving a threaded cowling on the male side of the connectors. The ends of the respective cowlings are equal with or extends past the end of the male connector. The threads on the inner surface of the cowling mate with the threads on the outer surface of the female side of the connector to secure the male side to the female side. The above described signal connectors are designed for hand attachment and detachment of the connectors. BNC type connectors are generally used to couple signals up to 4 Ghz. N-type connector and APC-7 connectors couple signals up to 18 Ghz. SMA connectors couple signals up to 26 Ghz.
BMA or blind mate connectors are another type of high frequency connector designed for coupling high frequency signals between bulkheads of modules without the use of threaded coupling or bayonet type connections. Referring to FIG. 1, there is shown a cross-section view of male 10 and female 12 sides of a BMA connector 14 mounted on respective bulkheads or panels 16, 18. The male side 10 of the BMA connector, such as manufactured and sold by M/A-Com Division of Amp, Inc., Lowell, Mass., includes a shield sleeve portion 20 having a tapered exterior portion 22 at the free end. The shield sleeve portion 20 has a threaded portion 24 disposed away from the free end that receives a retaining nut 26. A radially extending hexagonal flange 28 is formed on the shield sleeve portion 20 that abuts against the bulkhead or panel 16. Extending away from the flange 28 in an opposite direction from the free end is a second mating portion 30. The second mating portion 30 may be configured to receive a coaxial cable, formed as a SMA connector, or the like. The free end includes a central signal conductor 32 extends into the shield sleeve portion 20 and has a base portion 34, and an extending free end portion 36 coaxial with the shield sleeve portion 20. The free end portion 36 has a narrower diameter than the base portion, providing a shoulder 38 facing the leading direction. The free end of the conductor 36 is recessed below the shield portion 20 to prevent damage and to ensure that the shield 20 is connected when the signal conductor 32 makes and breaks contact.
A female side 12 of the BMA connector 14 has a cylindrical sleeve 40 defining a cylindrical chamber 42. The outer surface 44 of the cylindrical sleeve 42 is threaded to receive a retaining nut 46. A radially extending hexagonal flange 48 is formed on the cylindrical sleeve 40 that abuts against the bulkhead or panel 18. The sidewalls 50 and floor 52 of the chamber 40 are lined with a leaf spring sleeve having side springs 54 bowing slightly into the chamber 40, and end spring portions 56 bowing into the chamber 40 from the floor. The side springs 54 compliantly grip the male shield portion 20, even if it were somewhat angularly displaced. For the BMA standard, displacements of up to 5 degrees are tolerated without degradation of the connection. The end spring portions 56 provide compliant contact with the end surface 22 of the male shield 10, tolerating a small range of insertion depths, so that the signal connection may establish the precise insertion depth. A central signal conductor 58 is a rigid sleeve having a bore 60 sized to closely receive the free end portion 36 of the male side conductor 32. The conductor 58 has a free end surface 62 that is recessed at adequate depth below the free end face of the shield sleeve 40 to protect against damage. In addition, the sleeve 40 extends to an adequate distance relative to the signal conductor 58 to ensure that the shield contact is already made when the signal contact connects and is still made when the signal contact disconnects.
The male 10 and female 12 sides of the BMA connector 14 are inserted through holes 70, 72 in the respective bulkheads 16, 18 with the respective hexagonal flanges 28, 48 abutting against the bulkheads. Respective retaining nuts 26, 46 are threaded onto the male and female sides and tightened against the bulkheads to secure the male and female sides to the bulkheads. The bulkheads are brought together such that the shield sleeve portion 20 of the male side 10 is inserted into the chamber 40 of the female side 12 with the compliant springs 54 of the female side gripping the male shield sleeve portion 20 to align the free end portion 36 of the male signal conductor 32 to the bore 60 of the female central signal conductor 58. The bulkheads 16, 18 are secured together with screws, nuts and bolts and the like (not shown) to provide the axial thrust recommended by the manufacture for optimum signal integrity.
BMA connectors are used in applications where traditional threaded type connectors cannot be used, such as coupling high speed signals from a VXI module to a system backplane. However, they have not been used as part of a measurement instrument or signal source front panel until recently. Tektronix, Inc, Beaverton, Oreg., the assignee of the instant invention, introduced the TDS7104 Oscilloscope with a TEKCONNECT(trademark) signal interconnect system using BMA connectors. The front panel of the oscilloscope has rectangular pockets with each pocket having one side of the BMA connector mounted therein. The other side of the BMA connector is mounted in the end of a rectangular body portion that contains circuitry associated with of a measurement probe, adapter connectors and the like. The body portion is inserted into the pocket portion with the two sides of the BMA connectors making contact. Mechanical latching elements in the pocket and body provide the axial thrust for securing the two sides together for optimum performance. The above described signal interconnect system is described in co-pending patent application titled xe2x80x9cElectronic Interconnect Device for High Speed Siganl and Data Transmissionxe2x80x9d, Ser. No. 09/716,080, filed Nov. 17, 2000.
What is needed is an adapter for a BMA connector that would allow the BMA connector to be used as a front panel connector. Such an adapter should be able to use existing BNA components. Further, the adapter should provide the axial thrust for a good connection without having to mount both sides of the BMA connector on bulkheads or panels. The adapter should also be easily attached and detached from the BMA front panel connector. The adapter should be of a small size so as not to require significant front panel space.
Accordingly, the present invention is to an electronic interconnect adapter for a bulkhead mounted high speed coaxial interconnect having a female side mounted on the bulkhead. The female side of the adapter has a central signal conductor and a coaxial shield sleeve defining a chamber having a compliant contact facility portion with the sleeve having a threaded exterior surface. The interconnect adapter has a male side of the high speed coaxial interconnect having a central signal conductor and a coaxial shield contact The shield contact is divided into first and second mating members by a radially extending flange disposed part way along the shield contact The male portion of the first mating member is flexibly gripped by the compliant contact facility portion of the female side chamber. The male side of the high speed coaxial interconnect is inserted through a central bore in a rotatable coupling bushing. One side of the bushing has an axially extending flange disposed around the bore with the flange having a threaded interior surface that threadably mates with the threaded exterior surface of the female side coaxial shield sleeve. The opposite side of the bushing has an axially disposed cavity with a diameter greater than the central bore forming a shoulder within the cavity that receives the flange on the shield contact. A radial slot is formed in the cavity adjacent to the shoulder that receives a retaining member that captures the flange between the shoulder and the retaining member to secure the male side of the high speed coaxial interconnect to the coupling bushing. The coupling bushing provides axial thrust of the first mating member into the chamber of the female side of the coaxial interconnect as the coupling bushing is threaded onto the coaxial shield sleeve.
In the preferred embodiment of the invention, the speed coaxial interconnect is a BMA connector. The second mating member on the male side of the speed coaxial interconnect may be adapted to receive a coaxial cable, formed as a SMA male interconnect, or the like. The flange is preferably an integrally formed and radially extending nut disposed part way along the shield contact and a circular washer having a diameter equal to or greater than the maximum diameter of the integrally formed nut with a central bore there through. The washer is positioned on the first mating member in abutting relationship with the integral nut. A retaining nut is threadably mounted on the threaded portion of the first mating member that secures the washer on the male side of the coaxial interconnect. Alternately, the nut and washer may be integrally formed on the coaxial shield contact of the male side of the coaxial interconnect. The coupling bushing is preferably circular in form having a knurled exterior surface. The objects, advantages and novel features of the present invention are apparent from the following detailed description when read in conjunction with the appended claims and attached drawings.